Stent delivery system

ABSTRACT

One preferred embodiment includes a stent delivery system including a retractable sheath and an outer stability sheath. The stability sheath freely rotates relative to the retractable sheath, relieving compression forces caused by twisting of stability sheath in when in a tortuous conformation.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/652,737, filed Jan. 12, 2007, now U.S. Pat. No. 8,808,346, whichclaims priority under 35 U.S.C. §119(e) to U.S. Provisional ApplicationNo. 60/759,136, filed Jan. 13, 2006 and to U.S. Provisional ApplicationNo. 60/789,734, filed Apr. 5, 2006, each of which is incorporated byreference in its entirety into this application.

FIELD OF THE INVENTION

This invention relates broadly to medical devices. More particularly,this invention relates to an instrument for delivering a self-expandingstent into a mammalian body and controllably releasing the stent.

BACKGROUND OF THE INVENTION

Transluminal prostheses are widely used in the medical arts forimplantation in blood vessels, biliary ducts, or other similar organs ofthe living body. These prostheses are commonly known as stents and areused to maintain, open, or dilate tubular anatomical structures.

The underlying structure of the stent can be virtually any stent design.There are typically two types of stents: self-expanding stents andballoon expandable stents. Stents are typically formed from malleablemetals, such as 300 series stainless steel, or from resilient metals,such as super-elastic and shape memory alloys, e.g., Nitinol™ alloys,spring stainless steels, and the like. They can also, however, be formedfrom non-metal materials such as non-degradable or biodegradablepolymers or from bioresorbable materials such as levorotatory polylacticacid (L-PLA), polyglycolic acid (PGA) or other materials such as thosedescribed in U.S. Pat. No. 6,660,827, the contents of which are herebyincorporated by reference.

Self-expanding stents are delivered through the body lumen on a catheterto the treatment site where the stent is released from the catheter,allowing the stent to automatically expand and come into direct contactwith the luminal wall of the vessel. Examples of a self-expanding stentsuitable for purposes of this invention are disclosed in U.S.Publication No. 2002/0116044, which is incorporated herein by reference.For example, the self-expanding stent described in U.S. Publication No.2002/0116044 comprises a lattice having two different types of helicesforming a hollow tube having no free ends. The first type of helix isformed from a plurality of undulations, and the second type of helix isformed from a plurality of connection elements in series with theundulations, wherein the connection elements connect fewer than all ofthe undulations in adjacent turns of the first type of helix. The firstand second types of helices proceed circumferentially in oppositedirections along the longitudinal axis of the hollow tube. This designprovides a stent having a high degree of flexibility as well as radialstrength. It will be apparent to those skilled in the art that otherself-expanding stent designs (such as resilient metal stent designs)could be used according to this invention.

The stent may also be a balloon expandable stent which is expanded usingan inflatable balloon catheter. Balloon expandable stents may beimplanted by mounting the stent in an unexpanded or crimped state on aballoon segment of a catheter. The catheter, after having the crimpedstent placed thereon, is inserted through a puncture in a vessel walland moved through the vessel until it is positioned in the portion ofthe vessel that is in need of repair. The stent is then expanded byinflating the balloon catheter against the inside wall of the vessel.Specifically, the stent is plastically deformed by inflating the balloonso that the diameter of the stent is increased and remains at anincreased state, as described in U.S. Pat. No. 6,500,248, which isincorporated herein by reference.

Stents are delivered to an implant site with the use of a deliverysystem. Delivery systems for self-expanding stents generally comprise aninner tubular member on which the stent is loaded and which may be fedover a guidewire, and an outer tubular member or jacket longitudinallyslidable over the inner tubular member and adapted to extend over thestent during delivery to the implant site. The jacket is retracted alongthe inner tubular member to release the self-expanding stent from theinner tubular member.

In several available delivery systems, the jacket and inner member arefreely movable relative to each other and must be separately manuallyheld in the hands of the physician. After the distal end of the systemis located at the implant site, the inner member must be held still toprevent dislocation. However, it is very difficult to maintain theposition of the inner member while moving the outer member to deploy thestent. As such, the degree of control during deployment is limited.Under such limited control there is a tendency for the stent to escapefrom the inner member before the jacket is fully retracted and jump fromthe desired deployment site. This may result in deployment of the stentat a location other than the desired implant site.

A handle may be provided to move the outer tubular member relative tothe inner tubular member with greater control. For example, MedtronicInc., utilizes a handle which can lock the inner tube and outer jacketrelative to each other and effect relative movement of the two to causedeployment of the stent. However, such handles have severalshortcomings. First, the handle is not particularly well suited to shortstents as there is little fine control. Second, the handle is notwell-suited to long stents, e.g., above 90 mm in length, as the linearcontrol requires the operator to change his or her grip duringdeployment in order to generate the large relative motion of the tubularcomponents. Third, it is possible for the stent to automatically releasebefore the jacket is fully retracted from over the stent. This isbecause the super-elastic expansion of the stent causes the stent toslip distally out of the deployment system before the operator retractsthe sheath. The result can be an unintentionally rapid and possiblyuneven deployment of the stent. Fourth, without reference to afluoroscope monitoring the stent, there is no manner to determine fromthe proximal end of the instrument the progress of stent deployment.Fifth, the construction of the inner tubular member and outer jacket maycause the inner member and jacket to be crushed during use. Furthermore,the inner tubular member is subject to compressive force duringdeployment and may deform while moving the stent from the desireddeployment location.

Another stent delivery system can be seen in the U.S. Publication No.2004/0006380 titled Stent Delivery System and U.S. Publication No.2005/0273151 also titled Stent Delivery System, the contents of whichare hereby incorporated by reference. Like other available stentdelivery systems, the designs in these publications provide a singleactuating mechanism for moving the outer jacket relative to the innertubular member, specifically shown as a thumbwheel.

In these designs, the retraction speed of the jacket member is limitedby both the user's ability to actuate the thumbwheel (i.e. the speed theuser can move their thumb) and the retraction ratio of the thumbwheel(i.e. the ratio of thumbwheel movement/rotation to jacket retraction).This “speed limit” can be especially difficult for a user when deployinglonger stents such as those between 100 and 200 mm in length, since itgreatly increases the stent deployment time. Further, the thumbwheel canhave only one retraction ratio, which increases the difficulty ofretracting the jacket at substantially different speeds.

What is needed is a stent delivery system that overcomes the limitationsof the prior art and facilitates the retraction of the jacket atdifferent speeds. Further, a stent delivery system is needed thatprovides the user with greater dynamic control of the jacket to increasedelivery precision while reducing the deployment time.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a stent deliverysystem that permits a high degree of control during the deployment ofthe stent.

It is another object of the invention to provide a stent delivery systemthat more easily retracts an outer jacket at different speeds.

It is another object of the invention to provide a stent delivery systemthat has multiple controls for retracting an outer jacket.

It is yet another object of the invention to provide a stent deliverysystem with independent outer jacket retraction controls that allowswitching from one control to another without a lag in the jacketretraction.

The present invention seeks to achieve these and other objects in onepreferred embodiment by providing a stent delivery system having threeindependent controls for retracting an outer jacket to deliver a stentor similar prosthesis. More specifically, the stent delivery systemprovides a thumbwheel, a thumb lever, and a pull ring which each engagea distal portion of the outer jacket. When any of the three controls areactuated, they create a proximal force on the jacket, retracting thejacket and releasing a stent on the distal end of the delivery system.

Preferably, the thumbwheel and the thumb lever retract the jacket by wayof a cord within the handle of the delivery system that engages aproximal portion of the jacket. The thumbwheel rotates a spool whichwinds up the cord and therefore causes the jacket to retract. The thumblever effectively increases the path of the cord within the handle bymoving against a region of the cord, also causing the jacket to retract.The pull ring is preferably connected to the proximal end of the jacket,allowing the user to directly pull the jacket in a proximal direction.

Each of the jacket controls can be configured to provide the user withdifferent retraction ratios (e.g. for every 1 cm of movement of thethumb lever the jacket retracts 2 cm). In this respect, the user can usedifferent retraction controls at different stages in the deliveryprocedure. For example, the user may wish to initially retract thejacket slowly to “flower” the stent, with the thumbwheel. However, oncethe stent has been flowered, the user may wish to more quickly retractthe jacket with the lower ratio of the thumb lever or pull ring. In thisrespect, the stent delivery system allows the user to more easilyretract the jacket at different speeds during the delivery procedure.

Additional objects and advantages of the invention will become apparentto those skilled in the art upon reference to the detailed descriptiontaken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a preferred embodiment of a deliverysystem according to the present invention;

FIG. 2 illustrates an exploded perspective view of the delivery systemof FIG. 1;

FIG. 3 illustrates a partially disassembled side view of the deliverysystem of FIG. 1;

FIG. 4 illustrates a partially disassembled perspective view of thedelivery system of FIG. 1;

FIG. 5 illustrates a partially disassembled perspective view of thedelivery system of FIG. 1;

FIG. 6 illustrates a side cross section view of a delivery portion ofthe delivery system of FIG. 1;

FIG. 7 illustrates a side cross section view of a distal end of thedelivery portion of the delivery system of FIG. 1;

FIG. 8 illustrates a side cross section view of a strain relief memberof the delivery system of FIG. 1;

FIG. 9 illustrates a perspective view of a spool of the delivery systemof FIG. 1;

FIG. 10 illustrates a perspective view of a thumbwheel of the deliverysystem of FIG. 1;

FIG. 11 illustrates a perspective view of a slider of a handle portionof FIG. 1;

FIG. 12 illustrates a perspective view of a slider of the deliverysystem of FIG. 1;

FIG. 13 illustrates a side view of the slider of FIG. 12;

FIG. 14 illustrates a perspective view of proximal end of the deliverysystem of FIG. 1;

FIGS. 15A-15D illustrate perspective views of cord paths according to apreferred embodiment of the present invention;

FIG. 16 illustrates side view of a delivery system according to thepresent invention;

FIG. 17 illustrates a partially disassembled side view of the deliverysystem of FIG. 16;

FIG. 18 illustrates a partially disassembled perspective view of thedelivery system of FIG. 16;

FIG. 19 illustrates a partially disassembled perspective view of thedelivery system of FIG. 16;

FIG. 20 illustrates a side cross section view of a preferred embodimentof a delivery system according to the present invention;

FIG. 21 illustrates a side cross section view of area 21 of FIG. 20; and

FIG. 22 illustrates a side view of a preferred embodiment of an axiallycompressible stability sheath according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-14 illustrate a preferred embodiment of a stent delivery system100 according to the present invention which includes multiplemechanisms for retracting an outer tubular member 124 (also referred toas a jacket or sheath in this specification) to deliver a prosthesis,such as a stent 160 in the current example. As seen in FIG. 1, the stentdelivery system 100 includes a thumbwheel 106, a deployment lever 108,and a rapid deployment ring 110, each providing a different approach toretracting the outer tubular member 124 and therefore deploying thestent 160 or other prosthesis.

Each of the three deployment controls provides different actuationmethods that facilitate deployment of the stent 160 at different speeds.For example, the thumbwheel 106 allows the user to slowly deploy thestent 160 with slow and precise thumb movement, while the rapiddeployment ring 110 provides the user leverage to deploy the stent 160in a more rapid fashion.

Additionally, some of the deployment controls can be configured toprovide different ratios of retraction (e.g. 1 cm of movement of thedeployment lever 108 moves the outer tubular member 124, 2 cm). Thus,some controls may provide “finer” retraction control (i.e. smallermovement of the outer tubular member 124) and other controls may providea “coarser” retraction control (i.e. larger movement of the outertubular member 124).

In this respect, the delivery system 100 provides the user with a wider,more dynamic range of deployment controls for more precisely deliveringthe stent 160 within a patient. Further, this range of deploymentcontrols can better accommodate different types of stents or prostheses,especially those of almost any length.

The stent delivery system 100 generally includes two main portions: astent delivery portion 104 and a handle portion 102. The stent deliveryportion 104 is the elongated catheter assembly which is inserted intothe patient to deliver the stent 160 at a desired location. The handleportion 102 is connected to a proximal end of the stent delivery portion104, allowing the user to position the stent delivery portion 104 withinthe patient and release the stent 160.

As best seen in FIGS. 1 and 6-8, the stent delivery portion 104 includesan inner tubular member 128 preferably composed of a relatively stiffsingle material (e.g. polyimide) that preferably forms a single innerlumen. This allows the inner tubular member 128 to maintain someflexibility while retaining the strength to be pushed through the innervessels of a patient.

With reference to FIG. 7, the distal end of the inner tubular member 128includes a reduced diameter region 127 between a distal dilator tip 126(preferably composed of polyimide) and a shoulder 129. The reduceddiameter region provides space to accommodate the stent 160 in anunexpanded position underneath the outer tubular member 124. Theshoulder 129 and the distal dilator tip 126 prevent the stent frommoving laterally on the inner tubular member 128, either proximallytoward the handle portion 102 or distally out from under the outertubular member 124. The delivery portion may also include pusher tubingthat is disposed over the inner tubular member 128, proximal to ashoulder 129, which further supports the stent 160 when the outertubular member 124 retracts during delivery. In this respect, the stent160 maintains its position within the stent delivery system 100,providing a predictable delivery for the user.

As also seen in FIG. 7, the distal end of the inner tubular member 128also includes flushing holes 130, which are positioned underneath thestent 160 in the reduced diameter region 127 and which lead to, and areunitary with, a passage (not shown) within the inner tubular member 128,along its axis. This inner passage or lumen connects to a liquid sourceon the proximal end of the stent delivery system 100 at luer adapter118, allowing the user to flush out the stent 160 prior to deliverywithin the patient.

As best seen in FIG. 6, the proximal end of the inner tubular member 128comprises a rigid area 156 composed of less flexible materials, such asmetals or hard plastics. This rigid area 156 is positioned within thehandle portion 102, allowing the outer tubular member 124 to be easilyretracted over the rigid area 156 without the inner tubular member 128bending or creasing. The movement of the outer tubular member 124 overthe inner tubular member 128 is discussed in greater detail below.

As previously mentioned, the outer tubular member 124 is positioned overthe inner tubular member 128 and can be moved relative to the innertubular member 128, particularly allowing the outer tubular member 124to cover and uncover the nnexpanded stent 160. Preferably, the outertubular member 124 is composed of a braided polyimide. Alternately, theouter tubular member 124 is composed of a coextruded, trilayerconstruction. The inner layer is preferably polytetrafluoroethylene(PTFE), fluorinated ethylene propylene (FEP), high density polyethylene(HDPE), or urethane. The middle layer is a wire braid, and morepreferably a 304V stainless steel flat wire braid of 1×3 (40 picks)construction, with wires having a 0.001 inch by 0.003 inch rectangularcross-section. Wires of other metals and alloys may also be used,including other stainless steel alloys, cobalt-chrome alloys, and otherhigh-strength, high-stiffness, corrosion-resistant metal alloys. Theouter layer is preferably a thermoplastic, melt processible,polyether-based polyamide, such as PEBAX®-7033 available from ModifiedPolymer Components, Inc. of Sunnyvale, Calif. In the extrusion process,the inner and outer layers are bonded to each other and encapsulate themetallic reinforcing middle wire layer to create an integrated tubing.This tubing exhibits high lateral flexibility combined with a highdegree of longitudinal stiffness (resistance to shortening), and alsohigh torqueability.

Referring to FIGS. 1, 6 and 8, stability sheath 122 and strain reliefmember 120 are connected to the handle portion 102 and are positionedover the outer tubular member 124. The strain relief member 120(preferably composed of Polyurethane or Pebax® polyether block amidesfrom Arkema) prevents sharp bends in the outer tubular member 124 nearthe handle portion 102, reducing stress or strain that may otherwise beintroduced on connection points between the handle portion 102 and theouter tubular member 124. The stability sheath 122 extends along aportion of the length of the outer tubular member 124 to reduce anyunintended movement of the stent delivery portion 104 while the outertubular member 124 is being retracted (e.g. sideways or curling movementdue to friction between the outer tubular member 124 and the innertubular member 128).

As best seen in FIGS. 1-5, the handle portion 102 preferably includesthree mechanisms for retracting the outer tubular member 124 relative tothe inner tubular member 128. Specifically, the handle portion 102includes the thumbwheel 106, the deployment lever 108, and the rapiddeployment ring 110 that each are used to cause retraction of the outertubular member 124 through different mechanisms within the handleportion 102.

Referring to FIG. 2-5 the retraction mechanisms are built on an innerframe member 146 that is enclosed by body shell members 132A and 132B.As seen in FIGS. 2 and 11 the inner frame member 146 includes anelongated slot 146A that extends most of the length of the frame member146. A slider 152, best seen in FIG. 11-13, is positioned through andengaged with the slot 146A so as to slide along the length of the slot146A. The slider 152 is also fixed to the proximal end of the outertubular member 124, preferably by an adhesive. Thus, as the slider 152slides from a distal end of the slot 146A to a proximal end of the slot146A, the outer tubular member 124 similarly moves over the rigid area156 of the inner tubular member 128.

Optionally, a portion of the slider 152 contacts rack 140 to provide atactile and audible “click” as the slider 152 slides proximally alongthe slot 146A. The teeth of the rack 140 also allow the slider 152 tomove in only a proximal direction by including an angled distal surfaceand a perpendicular proximal surface. Thus, the contacting portion ofthe slider 152 simply moves up and over the angled surface when movedproximally, but is stopped from movement by the perpendicular surfacewhen distal movement is attempted. These “one way” teeth prevent theuser from moving the outer tubular member 124 distally in an attempt torecapture a partially deployed stent 160.

The thumbwheel 106, deployment lever 108, and the rapid deployment ring110 can each apply force in a proximal direction to the slider 152,causing the slider 152 and therefore the outer tubular member 124 tomove in a proximal direction. As described in more detail below, eachdeployment control uses different mechanisms within the handle portion102 to create force on the slider 152. The distance the slider 152 moveswill vary between each deployment control based, at least in part, onhow the mechanisms of each deployment control are configured. Thesemechanisms and their possible configurations will become clear from thedescription below.

As seen best in FIGS. 2, 4, 9 and 10, the thumbwheel 106 providesproximal force on the slider 152 through use of a cord 180 wound on aspool 154 at one end and attached to the slider 152 at the other end.The cord 180 is either attached to or positioned around the slider 152so that increased tension on the cord 180 provides a proximal force onthe slider 152, ultimately causing movement of the both the slider 152and the outer tubular member 124.

Preferably the cord 180 is composed of a material that imparts little orno stretch to the length of the cord 180. For example, polyethylene,nylon, stainless steel wire, or braided stainless steel fibers. While acord 180 is preferred in the present preferred embodiment, almost anyflexible elongated member could be used, having different shapes,thicknesses, flexibilities and compositions. For example, a relativelyflat ribbon shape may be used or alternately a cord having a generallysquare cross section. In another example, the cord can be composed of asingle, continuous material such as all plastic, or multiple threadswoven together.

Turning first to the rotation of the spool 154, a side of the innerframe member 146 includes an axle 155 onto which the spool 154 and thethumbwheel 106 rotatably mount by way of apertures through theirrespective centers. When the handle portion 102 is fully assembled, thespool 154 is positioned within the thumbwheel 106, pressing against aside of thumbwheel 106.

As best seen in FIGS. 9 and 10, the thumbwheel 106 engages the spool 154with a “one way” engagement mechanism that allows the thumbwheel 106 toonly engage and rotate the spool 154 in one direction. In this respect,the user is limited to retracting the outer tubular member 124 only,preventing attempts to recapture a partially deployed stent 160.

The engagement mechanism includes raised members 106A, seen best in FIG.10, positioned in a circular pattern on the inner surface of thethumbwheel 106. Each raised member 106A includes a flat surface 106Bperpendicular to the inner surface of the thumbwheel 106 and an angledsurface 106C. The angled surface 106C of one raised member 106A ispositioned near the flat surface 106B of another raised member 106A,orienting all of the surfaces in a single direction (e.g. all angledsurfaces 106C face a clockwise direction while all flat surfaces 106Bface a counter clockwise direction).

The spool 154 includes two floating arms 154A having an outwardlyextending region 154B, positioned to have a similar circumferentialposition as raised members 106A. When the handle portion 102 isassembled, the extending region 154B contacts either the raised members106A or the space in between the raised members 106A, depending on therotational orientation of the thumbwheel 106. As the thumbwheel 106 isrotated in one direction, the flat sides 106B of the raised members 106Acontact the extending region 154B, causing the spool 154 to rotate andtherefore wind up the cord 180.

However, if the thumbwheel 106 is rotated in the opposite direction, theangled surface 106 contacts the extending region 154B, causing thefloating arm 154A to move towards the inner frame member 146. As thethumbwheel 106 continues to rotate, the extending region 154B passesover the top of raised member 106A until the end of the raised member106A is reached, at which time the floating arm 154A snaps back to itsoriginal position. Thus, the thumbwheel 106 rotates, but the spool 154is not engaged and therefore does not rotate, effectively limitingrotation of the spool 154 by the thumbwheel 106 to only one direction.

As previously described, rotation of the spool 154 winds one end of thecord 180, reducing the effective length of the cord 180 in the handleportion 102. However, the cord 180 must also be appropriately positionedwithin the handle portion 102 to create a proximal force on the slider152. This cord position or cord path can be more clearly observed bycomparing the exploded view of FIG. 2 with the cord 180 shown in FIG.15A. As seen in these figures, one end of the cord 180 is wrapped aroundthe spool 154, passing around stationary anchor member 150 that is fixedto the inner frame member 146, through a passage 108A of the movabledeployment lever 108, back around a stationary anchor 149 that is alsofixed on the inner frame member 146, then passing down along the side ofinner frame member 146, around anchor member 148 at the proximal end ofthe inner frame member 146 and extending back towards the distal end ofthe inner frame member 146, and finally terminating with a knot aroundslider 152. Each of the stationary anchors has curved surfaces uponwhich the cord 180 can easily travel. Thus, as the spool 154 rotates inone direction (depending which direction the spool 154 is configured towind the cord 180), the cord 180 pulls the slider 152 towards theproximal end of the handle portion 102.

The mechanisms of the deployment controls, as previously mentioned, canbe configured to change the retraction ratio of the outer tubular member124. In one example, the mechanisms of the thumbwheel 106 can bemodified by changing the size of the spool 154. More specifically, thesize of the spool 154 (i.e. the spool diameter) can be increased ordecreased to change the amount of cord 180 each rotation of thethumbwheel 106 takes up. For example, decreasing the size of the spool154 will reduce the amount of cord 180 taken up by each rotation of thethumbwheel 106 and therefore reduces the amount the outer tubular member124 is retracted. Similarly, increasing the size of the spool 154 willincrease the amount of cord 180 taken up by each rotation of thethumbwheel 106, increasing the amount the outer tubular member 124 isretracted.

Turning to the second deployment control, the deployment lever 108, canalso retract the slider 152 and therefore the outer tubular member 124by increasing tension on the cord 180 and therefore on the slider 152 aswell. As seen in FIGS. 1-5, the deployment lever 108 engages a topportion of the inner frame member 146 over a rack 144, sliding in aproximal direction along the top portion of the inner frame member 146.As the deployment lever 108 moves in a proximal direction, it increasesthe path the cord 180 takes to reach the slider 152, increasing thetension on the cord 180 and generating a proximal force on the slider152.

Like the thumbwheel 106 and the slider 152, the deployment lever 108only moves in one direction, allowing the user to only retract the outertubular member 124. This “one way” movement is preferably achieved witha direction arm 108B (FIG. 3) extending from a proximal end of theunderside of the deployment lever 108. This direction arm 108B includesan end portion that engages the teeth of a rack 144. As seen best inFIG. 3, the teeth of the rack 144 have a distal surface that is angledand a proximal surface that is generally perpendicular to the innerframe member 146. When the deployment lever 108 is moved in a proximaldirection, the direction arm 108B follows the angled distal surfaceupward, moving over and past each tooth. However, when the deploymentlever 108 is moved in a distal direction, the end of direction arm 108Bmoves against the perpendicular proximal surface of the tooth. Since theproximal surface is not angled beyond 90 degrees (i.e. beyond theperpendicular) the direction arm 108B is unable to move over the tooth.Thus, the direction arm 108B prevents the deployment lever 108 frommoving in a distal direction, to recapture the stent 160. Additionally,the position of the deployment lever 108 is maintained when the userrotates the thumbwheel 106, which may create a distal force on the lever108 as the tension on the cord 180 is increased.

Referring to FIGS. 2-5, the proximal movement of the deployment lever108 moves the slider 152 by effectively increasing the length of thepath that the cord 180 must take to reach the slider 152. As previouslymentioned, the cord 180 passes through the passage 108A of the movabledeployment lever 108, around the stationary anchor member 149 that isfixed on the inner frame member 146, down the length of the inner framemember 146, then around stationary anchor member 148 at the proximal endof inner frame member 146. As the deployment lever 108 is moved in aproximal direction, the passage 108A on the deployment lever 108 movesaway from the anchor member 149 that is fixed on the inner frame member146. As a result, the distance between the passage 108A and the anchormember 149 increases, creating a longer path for the cord 180. Since oneend of the cord 180 is fixed around the spool 154, the movement of thedeployment lever 108 in this manner causes the slider 152 and thereforethe outer tubular member 124 to move proximally. In this respect, theone-way, proximal movement of the deployment lever 108 can retract theouter tubular member 124 to deploy the stent 160 within the patient.

The rapid deployment ring 110 provides yet another method of retractingthe outer tubular member 124 within the handle portion 102. As seen bestin FIGS. 2-6, 11 and 13, the rapid deployment ring 110 is a pull tabhaving an elongated body and a sliding portion 110A shaped to slidablycouple to the outer tubular member 124, distal to the slider 152. Thesliding portion 110A preferably has an aperture that allows it to notonly be positioned onto the diameter of the outer tubular member 124,but also freely slide along its length.

As shown in FIGS. 11 and 13, when the rapid deployment ring 110 ispulled by the user in a proximal direction, the sliding portion 110Apushes on a distal side of the slider 152 in a proximal direction also,moving the slider 152 proximally and causing the outer tubular member124 to retract. Since the rapid deployment ring 110 via its slidingportion 110A applies direct force on the slider 152 without anyintervening mechanisms (i.e. in a 1:1 retraction ratio), the user isfree to retract the outer tubular member 124 at any speed they desire.This arrangement especially facilitates quick retraction of the outertubular member 124 that would otherwise be difficult using thethumbwheel 106 or deployment lever 108.

Referring to FIGS. 1 and 2, the ring portion of the rapid deploymentring 110 is positioned through a slot 114 in shell member 132A andstores on a raised column 112. The raised column 112 has a diameterabout the same size as the diameter of the aperture of the rapiddeployment ring 110, allowing the ring 110 to lock on to the raisedcolumn 112. Optionally, the raised column 112 may also include an“imprint” or depression around the raised column 112 which is the sizeand shape of the ring portion of the rapid deployment ring 110 and whichallows the ring portion to sit within the depression without fallingout. Thus, the rapid deployment ring 110 can be kept out of the way ifthe user decides to deploy the stent 160 with the thumbwheel 106 ordeployment lever 108. Further, since the sliding portion 110A can freelyslide along the outer tubular member 124 (i.e. is not fixed or adheredin place on the member 124), use of the thumbwheel 106 or deploymentlever 108 will not cause the rapid deployment ring 110 to come loosefrom the raised column 112 and move down the slot 144. In other words,the position of the rapid deployment ring 110 is not affected when otherdeployment controls are actuated by the user.

Preferably, as seen in FIGS. 11-13, the sliding portion 110A has a thin,side profile to allow a finger member 116A of a locking clip 116 to bepositioned over both the sliding portion 110A and the slider 152. Sincethe slider 152 has horizontally raised portions around both a proximaland a distal side of the finger 116A of the locking clip 116, the slider152 moves against this finger 116A and is prevented from lateralmovement. In this respect, the finger 116A of the locking clip 116 actsas a locking pin that prevents the stent 160 from accidentally beingdeployed during shipment or prior to insertion within a patient.

The retraction ratio for both the deployment lever 108 and thethumbwheel 106 can be further adjusted by changing the path of the cord180 within the handle portion 102. One preferred method of changing thisratio is to distribute the user's retraction force over an increased thenumber anchors (e.g. anchor members 148 or 149). In this respect, theanchor members and cord 180 act similar to a rope and pulley systemwhere additional anchors function as additional pulleys. Like a pulleysystem, the more anchors the cord 180 is positioned around, the less theouter tubular member 124 will move relative to either the thumbwheel 106or deployment lever 108 (and the easier it will be to move thethumbwheel 106 or deployment lever 108).

A more specific example of this concept can be seen in FIG. 15B in whichthe cord 180B is positioned in a configuration generally similar to thatof FIG. 15A. However, instead of terminating the cord 180B at the slider152, as seen in FIGS. 2-5, the cord 180 passes around the slider 152 andterminates at a rear anchor 151, as shown in FIG. 14 at the proximal endof inner frame member 146. In this respect, the thumbwheel 106 ordeployment lever 108 moves the outer tubular member 124 a smaller amountrelative to the configuration shown in FIG. 15A because of the pulleyeffect previously described.

Yet another specific example can be seen in FIG. 15C, which can becompared with the structures seen in FIGS. 2-5. In this example, one endof cord 180C is wrapped around the spool 154 as previously described,passing around a stationary anchor member 150 located on a top region ofinner frame member 146, through passage 108A of the movable deploymentlever 108, back around anchor member 148, forward around slider 152,back around anchor member 151, and finally tying through aperture 153which is located on a distal portion of the inner frame member 146.Similarly, the thumbwheel 106 or deployment lever 108 move the outertubular member 124 a smaller amount relative to the configurations shownin FIGS. 15A and 15B due to the previously described pulley effect.

FIG. 15D illustrates another example path of cord 180D which passesaround fewer anchor members and therefore provides a ratio of user inputto outer tubular member 124 movement close to 1:1. For comparison, FIG.15D can be compared with FIGS. 2-5 to appreciate the path of the cord180D. One end of the cord 180D is wrapped around the spool 154, thenpasses around stationary anchor member 150, through aperture 108A of themovable deployment lever 108, down around slider 152, then back to rearanchor 156 (seen best in FIG. 14).

The path of the cord 180 may be configured in a variety of otherarrangements according to the present invention to achieve a desiredretraction ratio. Typically, a retraction ratio that provides a slowerretraction (e.g. 2 cm of deployment lever 106 movement to 1 cm of outertubular member 124 movement) may be preferred for smaller stents (e.g.20-90 mm), while a retraction ration that provides a quicker retraction(e.g. 1 cm of movement of deployment lever 108 to 1 cm of movement ofouter tubular member 124) may be preferred for larger stents (e.g.90-170 mm). However, it should be understood that most ratios can beused for any commonly used stents lengths, leaving the ratio as a matterof preference for the user.

While both the thumbwheel 106 and the deployment lever 106 act on thecord 180 to retract the slider 152, it should be appreciated that thesetwo mechanisms act independently of each other and therefore do notaffect the relative performance of the other. In other words, if theuser switches between these two deployment controls, there will not be a“lag” as slack in the cord 180 is taken up by the second control.Instead, actuation of either deployment control maintains tension on thecord 180 so that movement of either deployment control will immediatelymove the slider 152. For example, if the deployment lever 108 isinitially moved, the cord 180 maintains tension so that subsequentrotation of the thumbwheel 106 causes immediate movement of the slider152.

By contrast, if the user initially pulls the rapid deployment ring 110,slack may be created in the cord 180. If either the thumbwheel 106 orthe deployment lever 108 is then moved, that slack in the cord 180 willfirst be taken up by their movement, causing a delay in the retractionof the outer tubular member 124 until tension in the cord 180 increases.If a user, who cannot see these inner mechanisms or slack in the cord180, is not expecting this delay, they may mistakenly think that thedelivery system 100 is broken or has finished deploying the stent 160.Thus, the independent arrangement of the thumbwheel 106 and thedeployment lever 108 provide a more consistent and predictabledeployment procedure.

In operation, the inner tubular member 128 is fed over a guidewire andguided to a target location within the patient. Typically, radiopaquemarkers within the distal end of the delivery system 100 are viewedfluoroscopically to confirm that the inner tubular member 128 hasachieved the desired location within the patient.

Once the user is satisfied that the delivery system 100 is in a desiredposition, the user actuates one of the three deployment controls.Typically, the outer tubular member 124 is retracted slowly at first,allowing the distal end of the stent 160 to expand or “flower” againstthe target tissue of the patient. While the user can initially retractthe outer tubular member 124 with any of the three delivery controls,the thumbwheel 106 and the deployment lever 108 may allow for a slowerand more controlled retraction since either can be controlled with onlythe user's thumb.

If the user desires to maintain a slow and highly controlled retractionof the outer tubular member 124, the thumbwheel 106 or deployment lever108 use may be continued until the stent 160 has been completelyuncovered and expanded against the target area. However, if the userdesires to quickly retract the portion of the outer tubular member 124that remains over the stent 160, the rapid deployment ring 110 caninstead be used for more rapid retraction. The user simply pulls therapid deployment ring 110 along slot 114 until the stent 160 has beenfully deployed. Once the stent 160 has been fully deployed, the deliverydevice 100 is retracted from the patient, completing the deliveryprocedure.

It should be appreciated that any of the three deployment controls canbe used by the user, alone or in various combinations, to retract theouter tubular member 124 and deliver the stent 160. While the use of thedeployment controls may rest largely with the preference of the user,other factors may contribute to such a selection. For example, shorterstents (e.g. 20-90 mm) may be deployed more effectively with theprecision of the thumbwheel 106 or deployment lever 108 while longerstents (e.g. 100-170 mm) may be more effectively deployed with acombination of the thumbwheel 106 initially and the rapid deploymentring 110 subsequently.

FIGS. 16-19 illustrate another preferred embodiment of a stent deliverysystem 200 according to the present invention. The stent delivery system200 is similar to the previously discussed stent delivery system 100,but lacks the deployment lever 108, providing the user with only thethumbwheel 106 and rapid deployment ring 110 to retract the outertubular member 124.

The stent delivery system 200 utilizes the same inner frame member 146and body shell members 132A and 132B by including a cover plate 210which is positioned over the rack 144 and over the sides of the innerframe member 146. The cover plate 210 blocks the aperture created by thebody shell members 132A and 132B where the deployment lever 108 ispositioned in the previously described delivery system 100.

Additionally, referring to FIGS. 17-19, the cover plate 210 includes anaperture 212 through which the cord 180 may be positioned. Since thedeployment lever 108 is not present in this preferred embodiment, theaperture 212 provides a passage similar to passage 108A of thedeployment lever 108. This aperture 212 allows the handle portion 202 toprovide similar cord path configurations as those shown in FIGS.11A-11D.

As best seen in FIGS. 17 and 18, the stent delivery system 200 alsoincludes support blocks 214 that are attached to the inner frame member146. The support blocks 214 form an aperture with the side of the innerframe member 146 which is positioned around rigid area 156 of the innertubular member 128. The additional support provided to the rigid area156 further reduces the likelihood that the rigid area 156 will bend orfold during retraction of the outer tubular member 124. This bending orfolding can result from friction between the inner tubular member 128and outer tubular member 124 during retraction of the slider 152.Additionally, these support blocks 214 can act as stops for the slider152, preventing the outer tubular member 124 from being retracted anyfurther.

It should be understood that different elements, assemblies, or aspectsof each embodiment can be removed from, added to, or combined with otherembodiments. For example, the support blocks 214 can be used with thestent delivery system 100. In another example, the preferred embodimentof FIG. 1 can include only the thumbwheel 106 and deployment lever 108,leaving off the rapid deployment ring 110. (This means that thedeployment lever 108 may be moved into the area otherwise occupied bythe rapid deployment ring. Additionally, a cover, similar to cover plate210 can be used to cover an open area, allow the manufacture to usesimilar parts (e.g. similar outer body member 132A and 132B for eachdesign).

While the stent delivery systems 100 and 200 have been primarilydescribed as delivering stents, these embodiments may be modified todeliver other prosthesis devices that can be delivered within aretractable outer tubular member 124.

In some situations, a stentor other device must be delivered within apatient through a convoluted delivery path. As the path of the deliverydevice becomes more tortuous, the delivery device itself may becomecontorted. In such situations, the ability of the stability sheath 122to transmit torque generated at the handle portion 102 may be reduced.In other words, a proximal end of the stability sheath 122 may twistwithout resulting in the same degree of twist to the distal end. In oneexample, the user attempts to rotate the handle portion 102 but thestability sheath 122 tends to “corkscrew” or twist and cause compressionon the outer tubular member 124. In some circumstances, such acompression force can inhibit the outer tubular member 124 fromretracting and therefore complicate stent deployment. In a worst case,such compression may result in tearing or other breakage of the deliverysystem, causing further complications.

FIGS. 20 and 21 illustrate another preferred embodiment of a stentdelivery system 300 according to the present invention that seeks toeliminate the possibility of twisting by the stability sheath 122.Generally, the stent delivery system 300 is similar to the previouslydescribed delivery systems of this specification except that thestability sheath 122 is configured for rotation relative to the otherelements of the system 300, and particularly relative to the handle 102and outer tubular member 124. As a result, rotation of the handleportion 102 of the delivery system 300 can occur without requiringrotation of the stability sheath 122.

As seen best in FIG. 21, this rotational capability of the stabilitysheath 122 is preferably achieved by providing a circular disc member304 near the proximal end of the stability sheath 122. This disc member304 is positioned within a circular cavity 302A within a distal end 302of the inner frame member 146. The circular cavity 302A is preferablyslightly larger than the disc member 304 to allow for rotation of boththe disc member 304 and the stability sheath 122 but not so large as tointroduce an undesirable amount of “play” in which the disc member canmove. The disc member 304 is preferably bonded to the stability sheath122 or can alternately be integrally formed with the stability sheath122. In this respect, the disc member 304 retains the axial position ofthe stability sheath 122 on the delivery device 300 while also allowingfree rotation of the stability sheath 122.

Since the above-described configuration results in the independentrotation of the stability sheath 122 relative to the delivery system300, it is desirable to minimize friction between the strain reliefmember 120 and the stability sheath 122. In this regard, a low frictioncoating may be applied to the inner passage of the strain relief member120 and the outer surface of the stability sheath 122. Alternately, alubricant may be introduced between these surfaces. Friction is alsopreferably minimized between the inner surface of the stability sheath122 and the outer surface of the outer tubular member 124. This furtherfacilitates independent rotation of the stability sheath 122.

In operation, the user advances the delivery portion 104 of the deliverydevice 300 into the patient and rotates the handle portion 102 toachieve a desired orientation of the delivery portion 104. As withpreviously described embodiments, the handle portion 102 and thedelivery portion 104 are fixed relative to one another and thus rotationof the handle portion 102 will result in corresponding rotation of thedelivery portion 104. However, due to the use of the circular discmember 304 described above, the stability sheath 122 is not forced torotate along with the delivery portion 104 or handle portion 102. As aresult the stability sheath 122 does not inadvertently inhibit (e.g.,through compression, friction, etc.) the movement of the deliveryportion 104 within the patient. Therefore complications during adelivery procedure are minimized.

FIG. 22 illustrates another preferred embodiment of a stent deliverysystem according to the present invention which seeks to reducecomplications resulting from twisting by the stability sheath 340. Whilethe preferred embodiment illustrated in FIGS. 20 and 21 seeks to preventtwisting, the present embodiment compensates for the effects of twistingby providing a region on the stability sheath 340 that compresses inlength. This allows for a proximal end of the stability sheath 340 toremain secured to the handle portion 102 while allowing a distal end ofthe stability sheath 340 to axially retract along with the outer tubularmember 124 if the two are frictionally engaged with one another.

The stability sheath 340 includes a plurality of circumferential crumplezones 342 located along a length of the sheath 340. Preferably, thesecrumple zones 342 are located near the proximal end of the sheath 340,just distal to the strain relief member 120. Each crumple zone 342 isconfigured to compress under axial pressure similar to an “accordion”region of a bendable straw. Therefore, if the stability sheath 340becomes twisted and thereby frictionally engages the outer tubularmember 124, the crumple zones 342 will compress in length when the userretracts the outer tubular member 124 (i.e., when the user retracts theouter tubular member 124 to deploy the stentor other prosthesis). Inthis respect, the crumple zones 342 allow the distal end of thestability sheath 340 to move with the outer tubular member 124 insteadof otherwise preventing retraction.

Preferably, the crumple zones 342 allow a length of axial compression atleast equal to the length of the prosthesis to be deployed. In otherwords, if the stability sheath 340 does bear down on the outer tubularmember 124, the crumple zones 342 will allow the stability sheath 340 tomove with the outer tubular member 124 until the prosthesis has beendelivered.

Preferably, each of the crumple zones 342 compress in length by foldingor buckling, similar to an accordion. In one example, this folding canbe achieved by decreasing the thickness of each crumple zone 342relative to the thickness of the surrounding portions of the stabilitysheath 340. When axial force is applied to the stability sheath 340(i.e. by retraction of the outer tubular member 124), the weaker areasof the crumple zones 342 buckle, decreasing the overall length of thestability sheath 340.

Crumple zones 342 with decreased thicknesses can be created with varioustechniques known in the art. For example, the zones 342 can be formed asa unitary part of the stability sheath 340. Alternately, areas ofdecreased thicknesses can be cut out or otherwise removed with laser ormechanical cutting tools. In another example, the areas of decreasedthickness can be created by adding additional layers of material aroundeach crumple zone 342.

In another preferred embodiment, each of the crumple zones 342 can becreated by introducing circumferential accordion-like creases along thestability sheath 340 (i.e. creases oriented inward and outward of thesheath 340 similar to a creased region of a bendable straw). In yetanother preferred embodiment, the crumple zones 342 can be created withperforations or small punctures to weaken the stability sheath 340 andpromote buckling.

In operation, the user advances the delivery portion 104 of the deliverydevice into the patient and rotates the handle portion 102 to achieve adesired orientation of the delivery portion 104. As with previouslydescribed embodiments, the handle portion 102 and the delivery portion104 are fixed relative to one another and thus rotation of the handleportion 102 will result in corresponding rotation of the deliveryportion 104. If such rotation results in the twisting of the stabilitysheath 340 on the outer tubular member 124, the crumple zones 342 willcompress in length as the outer tubular member is retracted. As a resultthe stability sheath 340 does not inadvertently inhibit (e.g., throughcompression, friction, etc.) the movement of the delivery portion 104within the patient. Therefore complications during a delivery procedureare minimized.

Another preferred embodiment according to the present invention seeks toeliminate twisting of the stability sheath 122 with a breakaway bondbetween the stability sheath 122 and the handle portion 102. Preferably,the sheath 122 and the handle portion 102 can be arranged similarly tothe embodiments of FIGS. 1-19. However, a reduced amount of bondingmaterial can be used to fix the stability sheath 122 to the frame member146, allowing the stability sheath 122 to break free under pressure andmove with the outer tubular member 124. The user can adjust the amountof “breakaway force” needed to break the stability sheath 340 free byvarying the amount and type of adhesive or bonding agent.

As the user rotates the handle portion 102 during a delivery procedurethe proximal end of the stability sheath 122 may twist relative to thedistal end, creating force on the bond between the stability sheath 122and the handle portion 102. As the force on the bond reaches apredetermined amount, it breaks, allowing the sheath 122 to eitheruntwist under its own force or remain twisted and therefore move withthe outer tubular member 124. In either scenario, the stability sheath122 is prevented from inhibiting the movement of the outer tubularmember 124 and therefore delivery of the prosthesis.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A stent delivery system, comprising: a firsttubular member having a distal end sized and shaped to receive a stentand a proximal end stiffer than the distal end; a second tubular memberbeing longitudinally slidable over said first tubular member; a handlebody; a strain relief element coupled to a distal end of the handlebody; a third tubular member being at least partially disposed over saidsecond tubular member, said third tubular member being longitudinallycompressible relative to said first tubular member and to said secondtubular member, extending distally of a distal end of the strain reliefelement, and coupled to the handle body; wherein the handle body iscoupled to said second tubular member to retract said second tubularmember relative to said first tubular member, and the strain reliefelement is at least partially disposed over the third tubular member. 2.The stent delivery system of claim 1 wherein the third tubular membercomprises a stability sheath distal of the strain relief element.
 3. Thestent delivery system of claim 1 wherein stability sheath comprises acrumple zone.